Oilfield tubulars, such as pipes, drill strings, casing, tubing, etc., may be used to transport fluids or to produce water, oil, and/or gas from geologic formations through wellbores. In various applications, a shoulder may be formed on an exterior of the tubular, e.g., for gripping the tubular and/or for connecting tools, such as centralizers, scrapers, cement baskets, etc, to the exterior of the tubular.
A variety of structures are employed to provide such shoulders. In some cases, integral pans of the tubular itself, such as expanded diameter sections, e.g., pipe joints at an end of the tubular, may be employed as the shoulder. In other cases, especially when a shoulder is needed between the ends of the tubular, a separate stop collar is generally fixed in position around the tubular to provide the shoulder. Such stop collars generally include a metal ring, which is either slid over an end of the tubular or hinged so as to receive the tubular laterally.
To fix the position of the stop collar on the tubular, the stop collars generally employ a gripping feature that engages the tubular. Such gripping features often include adhesives and/or marking structures, such as teeth or set screws. However, for some tubulars and/or applications thereof, marking the tubular may not be appropriate, either because marking the tubular damages the tubular or is otherwise incompatible with the application, or because the tubular may be too hard for marking structures to adequately bite into the tubular, resulting in inadequate holding forces. Adhesives, although suitable in a variety of stop collar applications, may lack sufficient durability or bonding strength to alone provide sufficient holding force.
In other situations, a tool may be connected directly to a tubular, such that it is movable or fixed in position relative to the tubular. Such tools may be connected to the tubular in generally the same way as a stop collar is attached to the tubular. Accordingly, gripping the tubular in the context of tool-attachment may be subject to the same or similar challenges as experienced in gripping the tubular in the context of a stop collar.